Polymeric materials

ABSTRACT

High pressure injection apparatus  2  for addition of a liquid formulation into a polymer melt stream at position  4  comprises pump assembly  6  upstream of an injector assembly  8 . Pump assembly  6  is arranged to increase the pressure of the liquid formulation to a high pressure (e.g. up to 400 bar) and to accurately meter the liquid formulation to the injector assembly  8  which is arranged to inject the liquid formulation into the polymer melt stream. The polymer melt may be spun, for example to produce Fully Drawn Yarn (FDY) or Partial Orientated Yarn (POY). The pump assembly  6  comprises a syringe pump  12  which comprises a tube  14  in which a piston  16  is slideably received and is arranged to urge liquid formulation  18  within the tube to an outlet  20  which is coupled to an inlet of injector assembly  8.

This invention relates to polymeric materials and particularly, although not exclusively, relates to incorporation of additives into polymeric materials, for example polyesters, such as in polyester fibre production. Preferred embodiments relate to production of samples of polyester fibres, for example having different colours, for evaluation.

WO2014/207472 A2 describes high pressure injection apparatus for addition of a liquid formulation, for example comprising a vehicle and a colourant into a melted polymeric material. The injection apparatus described includes a first pump which may be a diaphragm or progressing cavity pump (pcp) and a second pump which is a gear pump. The first and second pumps are arranged to raise the pressure of the liquid formulation and accurately meter it to an injector which is arranged to inject the formulation into the melted polymeric material. Downstream of the contact between the formulation and polymeric material, the mixture may be used to form sheet or fibre or other articles in extrusion or blow moulding processes.

The arrangement described in WO2014/207472 is advantageous for relatively long-term production of sheets, fibre and extruded and blow moulded articles, comprising polymeric materials and additives. However, disadvantageously, when it is required to start a new production run using a liquid formulation comprising a different additive, for example colour, it is time-consuming to clean down the first and second pumps (amongst other elements of the apparatus) to avoid any contamination of polymeric material used in the new production run with residual liquid formulation remaining in the first and/or second pumps (or associated apparatus) from the preceding run.

In some situations, it may be desirable to inject liquid formulations into melted polymeric materials for relatively short times. For example, in colour matching processes, customers for liquid colour formulations may demand to see sample parts or materials (e.g. fibre) made by incorporating a proposed liquid colour formulation into a polymeric material, before they commit to purchasing large quantities for production runs. In this case, therefore, it is desirable to be able to relatively quickly clean down injection apparatus for injecting liquid colour formulations into polymeric materials, so as to minimise down-time between short sample production runs and, therefore, optimise the rate of sample production. It can take several hours to clear down apparatus such as described in WO2014/207472 and, accordingly, it will be appreciated it is not suited for use in short production runs for producing samples.

It is an object of the invention to address the above problems.

According to a first aspect of the invention, there is provided injection apparatus for injecting a fluid formulation into a molten polymeric material, the apparatus comprising:

(a) a drive pump, said drive pump comprising a chamber for containing fluid formulation to be injected and a drive member, said drive member being linearly moveable within the chamber to drive fluid formulation downstream of the drive member to an outlet of the drive pump;

(b) an injector device downstream of the outlet of the drive pump and being arranged to inject fluid formulation received from said drive pump into molten polymeric material.

Said drive pump may be arranged to deliver fluid formulation at a pressure of at least 30 bar, preferably at least 60 bar, more preferably at least 80 bar or at least 100 bar. The drive pump may be operable to deliver fluid formulation at a pressure of less than 700 bar at said outlet. Such high pressures may be relevant in extrusion blow-moulding (EBM) processes. In preferred embodiments, the drive pump may be operable to deliver fluid formulation at a maximum pressure of less than 450 bar, preferably of no more than 200 bar.

Said chamber of said drive pump may have a maximum volume arranged to contain fluid formulation of less than 500 ml, for example of less than 400 ml. The aforementioned maximum volume suitably represents the maximum amount of fluid which can be contained in the chamber for containing fluid formulation to be injected. In some cases, the chamber may have a maximum volume of less than 300 ml, less than 200 ml or, in some cases, less than 150 ml.

Said chamber of said drive pump may have a minimum volume of at least 50 ml.

Said chamber of said drive pump is suitably circular in cross-section. Said chamber is preferably of substantially constant cross-section along its extent, for example in the region of said chamber which is arranged to contain fluid formulation in use. Said chamber may have a diameter of at least 10 mm, preferably at least 15 mm. Said diameter may be less than 50 mm, for example less than 40 mm. Said chamber may have a substantially constant cross-sectional area of less than 2000 mm², for example less than 1300 mm². Said substantially constant cross-sectional area may be at least 200 mm².

Said chamber may have a length of at least 10 cm, preferably at least 20 cm. for example in the region of said chamber which is arranged to contain fluid formulation in use. The length may be less than 50 cm, preferably less than 40 cm.

Said drive member is suitably arranged to slide within the chamber. Said drive member is preferably arranged only to move linearly within the chamber, suitably without any rotation. It may be arranged to move between a first position defining a maximum volume (e.g. wherein the chamber may be full of fluid formulation) and a second position defining a minimum volume (e.g. in which the drive member is arranged after it has driven substantially all the fluid formulation from the chamber).

Said drive member preferably has a contact face which is arranged to contact fluid formulation in use and drive it to said outlet of the drive pump, wherein said contact face substantially corresponds in shape and/or size to the shape and/or size of the cross-section of the chamber in which the drive member is moveable. Preferably, there is substantially no gap between the contact face and the wall which defines the chamber, suitably so that fluid is restricted (preferably prevented) from passing upstream of said contact face, in use. Said drive member preferably includes a seal, for example a resilient seal, for sealing the drive member within the chamber, suitably so as to facilitate restriction (preferably prevention in normal use) of the passage of fluid upstream of the face, for example between the drive member and said chamber. Said seal may comprise an O-ring, for example at least two O-rings, suitably associated with said drive member. The periphery of said contact face is preferably contained within a single plane which plane suitably extends substantially perpendicularly to the direction of travel of the drive member. Said contact face preferably defines a smooth, uninterrupted surface. Said contact face is preferably symmetrical about two planes which are suitably defined coaxially to the direction of travel of the drive member. Said contact face may be substantially planar, preferably across its entire extent.

Preferably, when said drive member is in its second position defining a minimum volume as described, said contact face faces (and preferably contacts) an outlet face of said chamber, wherein said outlet face includes an outlet via which fluid formulation can exit the chamber. Said outlet face is preferably substantially planar (preferably across its entire extent) and it suitably extends substantially perpendicularly to the direction of travel of the drive member. In said second position, said contact face and said outlet face make face to face contact. Preferably, in said second position, there is no gap defined between any planar part of said contact face and any planar part of said outlet face. Such an arrangement suitably ensures no dead spots between the drive member and chamber (e.g. between contact face and outlet face) which could contain fluid formulation when the drive member is in the second position, thereby making the drive pump substantially self-cleaning.

Said drive pump is preferably a syringe pump.

Said drive member of said drive pump is suitably operatively connected, for example via a coupling, to a force applying device which is suitably arranged to apply a force to the drive member to cause it to move within the chamber towards said outlet (for example between a first position wherein the chamber is full of fluid formulation and a second position in which the drive member is arranged after it has driven substantially all the fluid formulation from the chamber).

Said force applying device may be arranged to apply a linear force of at least 1000 N to the drive member. The maximum linear force may be less than 7000 N. Said force applying device suitably comprises a mechanical linear actuator; it is preferably arranged to translate rotational motion (e.g. of a stepper motor) to linear motion to drive the drive member. Said force applying device may incorporate a drive screw, for example a ball race screw. In a preferred embodiment, said drive screw is axially aligned with an elongate axis of the drive member, said drive member being linearly movable in the direction of said elongate axis. When a force applying means is arranged to apply a linear force to the drive member, a motor, for example a stepper motor, is suitably provided and, preferably, a rotational axis of said stepper motor is axially aligned with a rotational axis of said drive screw and/or said elongate axis of the drive member. Thus, in a preferred embodiment, the apparatus includes a motor, a drive screw and drive member which are axially aligned.

Said force applying device may include a motor, for example a stepper motor. Said motor is suitably operatively connected to said mechanical linear actuator (e.g. drive screw) and is preferably arranged to cause the actuator to move. Preferably, said device is arranged so that linear movement of the drive member and/or said mechanical linear actuator is directly proportional to the number of revolutions of said motor. A gear box may be provided and arranged to adjust the output (rpm) of the stepper motor.

Said apparatus may be arranged so that, in use, the minimum revolutions per minute (rpm) of said motor is 0.50 rpm, for example 0.65 rpm. The maximum rpm of said motor may be 200 rpm.

Said injection apparatus may be arranged so that, in use, the minimum linear displacement of said drive member is 0.30 mm/minute, for example at least 0.50 mm/minute. The maximum may be less than 5.00 mm, for example less than 3.00 mm per minute.

Said injection apparatus may be arranged so that, in use, a minimum of at least 0.20 ml/minute (e.g. at least 0.30 ml/minute) of fluid formulation can pass out of said outlet. The maximum may be less than 10.00 ml/minute, preferably less than 2.00 ml/minute.

Said injection apparatus may be arranged so that, in use, a minimum of at least 0.2 g/minute (e.g. at least 0.30 g/minute) of fluid formulation can pass out of said outlet. The maximum may be less than 10.00 g/minute, for example less than 2.00 g/minute.

Said injection apparatus preferably includes only one pump which is arranged to increase pressure of fluid formulation and said one pump is said drive pump. Said injection apparatus preferably includes no pump other than said drive pump.

Said injection apparatus is preferably arranged to meter fluid formulation passing from said outlet by control of the rate of movement of said drive member within the chamber. Said apparatus preferably does not include any other device independent of said drive pump for measuring or metering fluid formulation passing from said outlet.

Said drive pump and said injector device are preferably releasably securable relative to one another. A releasably securable coupling device is preferably arranged to releasably secure the drive pump relative to the injector device.

Said injector device suitably includes a valve which may be arranged to be opened or closed for controlling passage of fluid formulation downstream of the device. Said valve is preferably arranged to withstand a fluid pressure of at least 100 bar, for example at least 150 bar or 200 bar.

Said valve is preferably arranged to withstand said fluid pressure in opposing directions. For example, it is preferably arranged to withstand said fluid pressure impinging on it from fluid formulation driven from the outlet of the drive pump and also to withstand pressure which may impinge it from molten polymeric material into which the injection apparatus is arranged to inject fluid formulation. Said valve may be arranged to be opened when the pressure of fluid formulation in the injector device is at least 1 bar, for example at least 2 bar or at least 4 bar, greater than the pressure of molten polymeric material at the position at which fluid formulation is injected into said molten polymeric material. The valve may be arranged to be opened when the difference in pressure between the pressure of the fluid formulation and the pressure of molten polymeric material is less than 10 bar, for example less than 7 bar.

Said injection apparatus preferably includes a pressure sensor for sensing, preferably measuring, the pressure of fluid formulation downstream of the drive pump. The pressure sensor may be arranged to measure pressure within a chamber of the injector device. The pressure in the chamber may be equal to the pressure within the chamber of the drive pump in operation. Said pressure sensor may be arranged to communicate information or pressure sensed to a processing unit associated with the injection apparatus, as hereinafter described.

Said drive pump is preferably releasably securable to said injector device. Said drive pump may include a male element or a female element arranged to releasably engage the other one of a male or female element associated with said injector device. Said male and female elements preferably comprise co-operable screw-threaded elements. Said male element is preferably screw-threaded and preferably associated with said drive pump and said injector device is preferably screw-threaded and is preferably a screw-threaded socket. Said drive pump is preferably arranged to be directly releasably secured to the injector device, suitably with no separate conduit positioned therebetween.

Said injection apparatus may be provided in combination with polymer supply apparatus for supplying molten polymeric material. Said polymer supply apparatus may comprise melt-processing apparatus. Said injector device may be arranged to inject fluid formulation, in use, into melted polymeric material associated with said polymer supply apparatus. A pressure measuring device is preferably provided for assessing the polymer pressure of molten polymeric material associated with said polymer supply apparatus, suitably at a position upstream of the position wherein fluid formulation is arranged to be injected into the melted polymeric material. Information relating to said polymer pressure may be arranged to be communicated to a processing unit associated with the injection apparatus.

Said injection apparatus may be provided in combination with a mixer arranged to mix fluid formulation injected from said injection device and molten polymeric material, for example from said polymer supply apparatus. Said mixer may be a static or dynamic mixer but is preferably a dynamic mixer, for example a cavity transfer mixer. Said mixer is preferably positioned downstream of said injector device.

Said injection apparatus may be provided in combination with a polymeric material forming device in which molten polymeric material is formed into a solid product for example a sample part (e.g. a sample swatch or part comprising material and one or more additives introduced via said fluid formulation) or material (e.g. fibre) comprising polymeric material and one or more additives introduced via said fluid formulation. To the aforementioned end, said injection apparatus may be in combination with a melt processing apparatus, for example extruder or injection moulding machine and/or a spinning machine. In a preferred embodiment, said injection apparatus is in combination with a spinning machine arranged to spin fibre from polymeric material into which fluid formulation has been injected. Said injection apparatus may be in combination with apparatus for extrusion blow-moulding.

A processing unit is preferably associated with said injection apparatus. The unit may be programmed so that an operator can set the rate of delivery of fluid formulation from said injection apparatus, for example from said drive pump and/or injector device thereof. The unit may be arranged to open and/or close a valve associated with said injection device suitably for controlling passage of fluid formulation into molten polymer material. The unit may be arranged to receive information relating to the pressure of liquid formulation in the injection apparatus and/or the pressure of molten polymeric material associated with polymer supply apparatus. For example, the unit may communicate with the pressure measuring device (when provided) which is for assessing the polymer pressure of molten polymeric material associated with said polymer supply apparatus and/or may communicate with a pressure sensor for sensing the pressure of fluid formulation downstream of the drive pump. The processing unit may be arranged to receive information relating to throughput of polymeric material in an associated melt processing apparatus. The unit may be arranged to receive information relating to the let-down-ratio for a combination of polymeric material and/or fluid formulation associated with the injection apparatus.

A user-interface may be associated with the injection apparatus. Said user interface may communicate with said processing unit. One or more of the following variables may be input via said user interface:

-   -   the rate of throughput of polymeric material in a polymer supply         apparatus;     -   the identity and/or characteristics of the drive pump used;     -   the specific gravity of the fluid formulation to be injected;         and     -   the desired addition rate of fluid formulation into the         polymeric material.

Preferably, the user-interface is arranged for input of two, three or all four of the aforementioned variables.

The invention extends to injection apparatus which includes a fluid formulation within said chamber. Said fluid formulation may have any feature of the fluid formulation described hereinafter.

The invention extends to injection apparatus which includes a molten polymeric material (e.g. thermoplastic polymeric material) in a polymer supply apparatus as described. Said polymeric material may have any feature of the polymeric material described hereinafter.

According to a second aspect of the invention, there is provided a method of injecting a fluid formulation into a molten polymeric material, the method comprising:

(i) selecting an injection apparatus comprising a drive pump, said drive pump comprising a chamber containing fluid formulation to be injected and a drive member, said drive member being linearly moveable within the chamber to drive fluid formulation downstream of the drive member to an outlet of the drive pump;

(ii) operating the drive pump to drive fluid formulation towards molten polymeric material; and

(iii) injecting said fluid formulation into molten polymeric material.

Said method may use injection apparatus of the first aspect.

Said drive pump may be as described in the first aspect.

Step (iii) in the method may use an injector device as descried in the first aspect.

Advantageously, the method may be used to dose relatively viscous formulations which may have high loadings of additives into molten polymeric material.

Unless otherwise stated, viscosity described herein may be measured using a Brookfield Viscometer at 20 rpm and 23° C.

Said formulation may have a viscosity of at least 5000 cP, suitably at least 10000 cP, preferably at least 15000 cP. The viscosity may be less than 250,000 cP.

Said fluid formulation may include vehicle and one or more additives. An additive may be selected from colourants, UV filters, oxygen absorbers, antimicrobial agents, acetaldehyde scavengers, reheat additives, antioxidants, light stabilizers, optical brighteners, processing stabilizers and flame retardants.

Said fluid formulation may include at least 20 wt %, preferably at least 35 wt %, more preferably at least 50 wt % of additives. Said formulation may include less than 85 wt % of additives. Said fluid formulation may include at least 15 wt % of liquid.

Preferably, said fluid formulation includes at least 20 wt % of colourant which may comprise one or more colourants. The total amounts of colourants in said fluid formulation may be at least 30 wt %, at least 45 wt % or at least 55 wt %. Colourants may be pigments or dyes. Said fluid formulation may include colourants which are insoluble in the vehicle at STP.

Said fluid formulation may include 15 to 80 wt % of vehicle and 20 to 85 wt % of additives.

Said fluid formulation may include a vehicle which is suitably a liquid at STP. Said vehicle preferably has a boiling point (at a pressure of 760 mmHg) of greater than 300° C., preferably greater than 350° C., more preferably greater than 500° C. The boiling point may be less than 1150° C. or less than 1000° C. The melting point of the vehicle may be less than 0° C. or less than −10° C.

Said vehicle is preferably a liquid vehicle. Illustrative liquid vehicles include but are not limited to: mineral oils, C₉-C₂₂ fatty acid esters, ethoxylated C₉-C₂₂ fatty acid esters, ethoxylated alcohols and plasticizers. Plasticizers may for example be sebacates and azelates, such as dibutyl sebacate, esters such as benzyl benzoate, adipates such as dioctyladipate, citrates such as triethyl citrate, epoxies, phosphate esters such as 2-ethylhexyl diphenyl phosphate, phthalates such as dioctylphthalate, and secondary plasticisers such a chlorinated paraffins.

The method may comprise selecting a volume of fluid formulation for use in the method. The volume selected may be less than 500 ml. The method may include a step of preparing less than 500 ml of said fluid formulation.

The method may comprise introducing fluid formulation into said chamber of said drive pump, wherein less than 500 ml, for example less than 400 ml of said fluid formulation is introduced into said chamber.

In step (iii) of the method, fluid formulation may be injected into molten polymeric material at a pressure of at least 30 bar, preferably at least 60 bar, more preferably at least 80 bar, especially at least 100 bar. The pressure may be less than 700 bar or less than 130 bar.

In the method, a motor which is operatively connected to the drive member, to drive it forward, may be operated at least 0.50 rpm, for example at least 2.00 rpm. It may be operated at less than 10 rpm.

In the method, said drive member may be moved at a rate of at least 0.20 mm/minute, preferably at least 0.50 mm/minute. It may be moved at a rate of less than 5 mm/minute, for example less than 2 mm/minute or less than 1 mm/minute.

In the method, fluid formulation may be delivered into the polymer material at a rate of at least 0.10 ml/minute, preferably at least 0.25 ml/minute. It may be delivered at a rate of less than 2.00 ml, preferably less than 1.00 ml/minute or less than 0.70 ml/minute.

In the method, less than 500 ml, preferably less than 300 ml, more preferably less than 200 ml of fluid formulation is delivered into the polymeric material during one run, for example during one uninterrupted injection of said fluid formulation into molten polymeric material. At least 50 ml, or at least 100 ml may be delivered.

Prior to step (iii), the method may comprise inputting the let-down-ratio (LDR) into a processing unit via a user-interface.

Prior to step (iii), the method may comprise a user inputting the specific gravity of the fluid formulation to be injected, for example via a user interface into a processing unit.

Prior to step (iii), the method may comprise a user inputting a desired dose rate (or information relating to a desired dose rate) at which the fluid formulation is to be dosed into the molten polymeric material. Input may be via a user interface into a processing unit.

Injection in step (iii) may be carried out continuously for at least 2 minutes, for example at least 8 minutes. Injection in step (iii) may be carried out continuously for less than 60 minutes, preferably less than 30 minutes, more preferably less than 20 minutes. After said continuous injection, a first sample is produced according to a first set of variables (e.g. identity, such as colour of fluid formulation or LDR); thereafter, the method may be repeated using a second set of variables to produce a second sample.

Preferably, fluid formulation is selected and injected at a rate which introduces less than 10 wt %, more preferably less than 7 wt %, or less than 4 wt % of vehicle into the melted polymeric material. At least 0.01 wt % or at least 0.10 wt % of vehicle may be introduced. That is, after contact between formulation and melted polymeric material, the amount of vehicle in the mixture is preferably less than 10 wt %, less than 7 wt % or less than 4 wt %. The amount may be at least 0.01 wt % or at least 0.10 wt %. Preferably, after contact between fluid formulation and melted polymeric material, the sum of the amounts of all liquids introduced into the polymeric material via said fluid formulation is less than 10 wt %, less than 7 wt % or less than 4 wt %, based on the total weight of mixture comprising said fluid formulation and said melted polymeric material after said contact. The sum may be at least 0.01 wt % or at least 0.1 wt %.

Preferably, fluid formulation is selected and injected at a rate which introduces less than 10 wt %, more preferably less than 7 wt %, or less than 4 wt % of additives into the melted polymeric material. At least 0.01 wt % or at least 0.10 wt % of additives may be introduced. That is, after contact between fluid formulation and melted polymeric material, the amount of additives in the mixture is preferably less than 10 wt %, less than 7 wt % or less than 4 wt %. The amount may be at least 0.01 wt % or at least 0.10 wt %. Preferably, after contact between fluid formulation and melted polymeric material, the sum of the amounts of all liquids introduced into the polymeric material via said fluid formulation is less than 10 wt %, less than 7 wt % or less than 4 wt %, based on the total weight of mixture comprising said fluid formulation and said melted polymeric material after said contact. The sum may be at least 0.01 wt % or at least 0.1 wt %.

Preferably, said polymeric material comprises a synthetic thermoplastic polymer. Said polymeric material is preferably able to be formed into fibres. Said polymeric material may be a condensation polymer, for example a condensation polymer which may depolymerise in the presence of water and/or a carrier with appropriate functional groups (which could include but is not limited to hydroxyl and carboxylic acid species). Said polymeric material may be selected from polyesters, polyamides, polyalkylene polymers (e.g polypropylene and polyethylene), polycaprolactone, polycarbonates, acrylics and aramids. In one preferred embodiment, said polymeric material is a polyester. In another embodiment, it may be a polyalkylene (e.g. polyethylene such as HDPE, usable in extrusion blow-moulding).

Examples of polyamides include aliphatic PA6 and PA6,6, semi-aromatic polyphthalamides (e.g. PA 6T) and aromatic polyamides in which at least 85% of the amide linkages, (—CO—NH—) are attached directly to two aromatic rings—for example the para-aramids.

Said polymeric material preferably comprises a polyester which may be selected from poly(ethylene terephthalate) (PET), poly(butylene terephthalate) (PBT), poly(trimethylene terephthalate) (PTT), poly(ethylene naphthalate) (PEN), poly(1,4-cyclo-hexylenedimenthylene) terephthalate (PCT), poly(ethylene-co-1,4-cyclohexylenedimethylene terephthalate) (PETG), copoly(1,4-cyclohexylene dimethylene/ethylene terephthalate) (PCTG), poly(1,4-cyclohexylene dimethylene terephthalate-co-isophthalate) (PCTA), poly(ethylene terephthalate-co-isophthalate (PETA), poly(lactic acid (PLA), poly(glycolic acid) (PGA) and their blends of copolymers. Said polymeric material preferably comprises, more preferably consists essentially of PET.

A typical spinnable condensation polymer such as polyester, for example PET, may have up to 250 or up to 200 repeat units (e.g. molecular weight of up to 25,000 or up to 20,000). The number of repeat units may be in the range 50-200, suitably 75-200, preferably 75-125 repeat units. A typical spinnable polymer may have about 100 repeat units. The condensation polymer may be linear and be able to reach the high levels of orientation and crystallinity which are induced during spinning and drawing processes.

Typical spinnable polyesters have an IV in the range 0.62 to 1 dl/g. Preferred polyesters have an IV within the range of 0.5 to 1.2 dl/g when measured using standard techniques (for example ASTM D4603-03).

Downstream of step (iii) of the method, a polymeric material forming device may be used, wherein molten polymeric material after contact with said fluid formulation is formed into a solid product (e.g. a sample swatch or part comprising polymeric material and one or more (preferably a plurality) of additives introduced via said fluid formulation).

Downstream of step (iii), polymeric material after contact with said fluid formulation may be melt-processed, for example extruded, inject-moulded or spun. Preferably, it is spun to produce a fibre sample.

After injection in step (iii), one or more samples may be produced for example by extrusion, injection moulding or spinning. The total weight of said one or more samples produced in a run (e.g. without refilling the chamber of said drive pump with fluid formulation) may be less than 5 kg, preferably less than 2 kg, more preferably less than 1 kg, especially less than 600 g. The total weight may be at least 50 g or at least 100 g. The aforementioned total weights may represent, for example, the weight of a sample of fibre produced in the method.

Advantageously, the method can be used to introduce, over a short space of time, a series of different fluid formulations or the same fluid formulation at a different let-down-ratio (LDR) into molten polymeric material to enable different samples to be produced comprising polymeric material and additives, for example colourants, for evaluation. For example, a first fluid formulation may be introduced at a first LDR into molten polymeric material over a period of less than 1 hour for example less than 30 minutes. Thereafter, the same first fluid formulation may be introduced at an LDR different to the first LDR; or a second fluid formulation different to the first fluid formulation may be introduced. Thus, the invention extends to carrying out a first method according to said second aspect using a first fluid formulation having any feature of the fluid formulation described; and carrying out a second method according to said second aspect, said second method using the same drive pump as said first method. Where the only difference between the first and second methods is the LDR, this may be changed without any cleaning of the drive pump. Where the difference between the first and second methods is the nature of the fluid formulation (e.g. the colour), the drive pump may be cleaned (as necessary) between carrying out the first and second methods. Thus, the second method may differ from the first method in using a different fluid formulation compared to that used in the first method or using the same fluid formulation but at a different LDR.

Since the apparatus and method described may be advantageously used to inject fluid formulations into polymeric materials at high pressure for a short time and easily and quickly cleaned after such injection, the apparatus and method may advantageously be used in colour-matching processes to provide sample parts or materials to customers wishing to select a suitable fluid formulation for a production run. Thus, in a third aspect there is provided a method of selecting a colour formulation for manufacturing, in a selected colour, a sample wherein said sample comprises a polymeric material, the method comprises:

(i) selection of a first trial colour formulation;

(ii) injecting said first trial colour formulation into a molten polymeric material using an injection apparatus comprising a drive pump, said drive pump comprising a chamber for containing fluid formulation to be injected and a drive member, said drive member being linearly moveable within the chamber to drive fluid formulation downstream of the drive member to an outlet of the drive pump;

(iii) after said injection, producing said sample;

(iv) assessing said sample produced to determine if its colour is acceptable;

(v) optionally selecting one or more other trial colour formulations or selecting a different let-down-ratio (LDR) for injection into molten polymeric material and repeating steps (ii) to (iv) until it is determined that the colour of the sample is acceptable.

Said injection apparatus may have any feature of the injection apparatus described according to the first and/or second aspect.

Said method of the third aspect may include injecting said first trial formulation and, optionally, any other trial formulation having features as described for said fluid formulation, following the method of the second aspect.

Selection of said first trial colour formulation may involve:

(I) at a first location, determining colour information relating to a desired colour for sample;

(II) communicating colour information determined in step (I) to a second location;

(III) at the second location, determining one or more colour formulations for delivery into said polymeric material to match or closely match the desired colour;

(IV) delivering information relating to the colour formulation (s) determined in step (III) to an assessment location for assessment;

(V) optionally repeating step (III) to determine one or more additional colour formulations for delivery into the polymeric material to match or closely match the desired colour;

(VI) the selection of one or more trial colour formulations for use in the manufacture of said sample.

In step (I) of the method, colour information may be determined by selecting an identifier of a colour in accordance with a defined colour system (e.g. RAL or Pantone) or a colour spectrum of the desired colour may be determined. The latter is preferred. When an identifier of a colour in a defined colour system is selected, the identifier may be converted into colour data, for example a colour spectrum.

In step (I), the method may comprise spectrophometrically assessing the desired colour to determine said colour information. This may be done using a portable spectrophotometer (e.g. a hand held unit) or may be done using a substantially immobile spectrophotometer. The method may therefore comprise a step (I) which comprises presenting a sample of a desired colour to a spectrophotometer to determine its spectrum in the visible region. The spectrum in the IR and UV regions may also be determined.

The first location may be a customers premises or premises of a designer.

In step (II), said colour information is preferably communicated to a second location which is remote from said first location. For example, said first and second locations may be more than 10 or 100 miles away from each other; they may be in different towns or countries.

In step (III), said one or more colour formulations may be selected having regard to one or more of the following variables, in addition to the variable of colour information:

(a) the identity of the polymer into which the colour formulation is to be incorporated. For example, the polymer may be virgin polymer; or it may be recycled polymer, for example PCR.

(b) the grade of polymer into which the colour formulation is to be incorporated;

(c) the processing conditions to which the polymer into which the colour formulation is to be incorporated will be subjected. Such processing conditions may be relevant to heat stability requirements of materials in the colour formulation.

(d) the use and/or requirements of the part for which the colour formulation is to be selected, for example, the light fastness, weather fastness, chemical resistance (when in contact with other parts or products such as fluids);

(e) country of use. In this case, a colour formulation will only be delivered which complies with relevant local laws.

Computing means is preferably provided in said second location. Said computing means is preferably arranged to receive information determined in step (I) and determine a match or close match of the desired colour. Said computing means preferably includes a database which comprises information relation to a multiplicity of base colour formulations included in a colour dispense system which is arranged to be used to dispense the colour formulations to produce a mixture which suitable defines a fluid formulation described herein, for use in producing a sample. Said computing means preferably includes information relating to the spectra in the visible region of each of said base colour formulations. Said computing means preferably includes information relating to properties and/or effects of said base colour formulations when incorporated into different types of thermoplastics.

Said computing means preferably includes means for determining the effect, for example the colour spectrum, resulting from mixing a plurality or a multiplicity of base colour formulations. Additionally, said computing means may be arranged to determine the effect of adding a mixture of a plurality or multiplicity of base colour formulations to different types of polymeric materials.

Said computing means preferably includes means for determining the effect of adding a mixture of a plurality or multiplicity of base colour formulations at different concentrations into a polymeric material. The computing means may also determine the concentration at which the colourant should be added and the addition rate.

In step (III), preferably a plurality of colour formulations for delivery into a polymeric material are determined. The colour formulations may differ from each other on the basis of the closeness of their colours to the desired colour and/or their relative cost.

After selection of one or more trial colour formulations described in step (VI), each trial colour formulation may be manufactured, suitably in low volume (e.g. less than 500 ml). Manufacturing may use a colour dispense system which includes a multiplicity of base colour formulations arranged to dispense predetermined amounts of base colour formulations into a receptacle.

The colour dispense system may include more than 10, preferably more than 20, more preferably more than 25 base colour formulations.

The method may comprise communicating information relating to the amounts of base colour formulations to be dispensed, suitably from a computing means as described.

Any invention described herein may be combined with any feature of any other invention or embodiment described herein mutatis mutandis

Specific embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings in which,

FIG. 1 is a block diagram representation of high pressure injection apparatus;

FIG. 2 is a schematic cross-section through a pump assembly;

FIG. 3 is a perspective view of a high pressure injection apparatus;

FIG. 4 is a graph showing weight of formulation displaced v. time for a high viscosity formulation; and

FIG. 5 is a schematic graph of a system for selecting and delivering liquid colour formulations for use in colouring thermoplastic polymeric materials.

In the figures, the same or similar parts are annotated with the same reference numerals.

Referring to FIG. 1, in general terms, high pressure injection apparatus 2 for addition of a liquid formulation into a polymer melt stream at position 4 comprises pump assembly 6 upstream of an injector assembly 8. Pump assembly 6 is arranged to increase the pressure of the liquid formulation to a high pressure (e.g. up to 400 bar) and to accurately meter the liquid formulation to the injector assembly 8 which is arranged to inject the liquid formulation into the polymer melt stream. The polymer melt may be spun, for example to produce Fully Drawn Yarn (FDY) or Partial Orientated Yarn (POY).

Referring to FIG. 2, the pump assembly 6 comprises a syringe pump 12 which comprises a tube 14 in which a piston 16 is slideably received and is arranged to urge liquid formulation 18 within the tube to an outlet 20 which is coupled to an inlet of injector assembly 8. Piston 16 is connected to a ball screw 22 which is coupled via coupling 24 to a stepper motor 26.

Referring to FIG. 3, the syringe pump is shown connected to injector 8. The injector 8 is arranged to be releasably secured to the syringe pump 12 and is arranged to inject liquid formulation into the polymer melt stream at high pressure. It includes a valve (not shown) which is arranged to withstand high pressure thereby enabling it to both shut off flow of liquid formulation from the pump 12 and prevent flow of polymer melt into the injector.

The pump assembly 6 is designed so it is capable of delivering the required volume of liquid formulation at the required pressure. In one embodiment, the piston 16 is of circular cross-section and has a diameter of 20 mm, meaning it has a surface area of 314.2 mm². Based on this area, the required linear force to deliver a pressure of 100 Bar on the liquid formulation 18 is 3150N. A standard ball race screw 22 is used with a dynamic linear force of 3400N and with a lead of 2 mm which implies the potential to deliver 108 Bar. The controller for the stepper motor had a minimum speed of 0.72 rpm. With a lead of 2 mm or less, a minimum piston displacement of 1.44 mm/min is achieved which equates to 0.45 ml/min with a 20 mm piston. If the liquid formulation has an average relative density of 1.2 g/cm³, the minimum displacement in grams of product is 0.54 grams per minute. With fibre being spun from polymer into which the liquid formulation is injected (e.g. using a FDY or POY machine) at about 4.5 kg per hour throughput of polymer (equivalent to 75 gram per minute), liquid formulation (e.g. liquid colour) could be delivered under pressure at a range of percentages from about 0.72 wt % upwards.

The apparatus described may be operated as follows:

(i) The assembly of FIG. 3 is split at position 30 (FIG. 3) to separate the pump 12 and injector 8 to allow the pump to be filled.

(ii) The piston 16 is driven back using the controller for the stepper motor.

(iii) Tube 14 is loaded with liquid formulation.

(iv) The pump 12 and injector 8 are reconnected.

(v) The apparatus is primed through the injector and, thereafter, a valve (not shown) of the injector 8 is closed.

(vi) The injector is operatively connected to a dynamic mixer which is arranged to mix liquid formulation and molten polymer.

(vii) A spinning machine (e.g. FDY or POY machine) downstream of the dynamic mixture is started.

(viii) The controller for the stepper motor is started at the desired throughput.

(ix) When the pressure of the liquid formulation in the injector is 4-6 bar greater than the pressure of the molten polymer delivered to the dynamic mixer, the injector 8 is opened to deliver liquid formulation, which is mixed with polymer in the dynamic mixer. Polymer incorporating liquid formulation (e.g. colour) is then spun, via the spinning machine.

(x) Once a run is completed (this may involve delivery of 5 to 50 ml of liquid formulation) the FIG. 3 assembly is disconnected from the dynamic mixer and the pressure released.

(xi) The assembly of FIG. 3 is split at position 30 and the piston 16 driven forward to evacuate any remaining colour within tube 14 or otherwise associated with pump 12. Advantageously, other than wiping outlet end 20 of pump 12, no further cleaning of it is required because the plunger is able to completely wipe the walls of tube 14 when it expels liquid formulation. Since the injector is arranged to have no dead spots, it can be cleaned by passing the next liquid formulation through it. The dynamic mixer may be cleaned by passing molten polymer through it.

The apparatus was tested as described in Examples 1 to 4.

EXAMPLE 1—PRESSURE GENERATION

The apparatus was tested to confirm if it is capable of generating the required pressure required without stalling. This was done off line by filling pump 12 with liquid formulation, purging the system, closing the injector and then slowly driving the system forward whilst measuring the pressure.

During the testing, the pump 12 was charged with liquid formulation and slowly the pressure was raised to 120 Bar. It was found the apparatus was easily capable of reaching and holding the pressure required.

EXAMPLE 2—DISPLACEMENT ACCURACY

The apparatus was set up off line over a data logging balance and the balance was set to record the mass every five seconds. The unit was run and the mass of liquid formulation captured in a container on the balance was recorded. This was repeated at a range of different speeds—0.72 rpm, 1 rpm, 5 rpm, 10 rpm, 20 rpm to 50 rpm.

The calculation for the displacement is as follows:

-   -   Distance traveled per revolution=2 mm     -   Radius of the piston—10 mm     -   Specific gravity of the liquid formulation=0.91 g/ml

Therefore each revolution of the motor will theoretically give:

-   -   Area of piston=π×10²=314.2 mm²     -   Volume displaced per revolution of motor=2×314.2=628.4 mm³     -   Volume displaced per revolution of motor in ml=0.6284 ml     -   Grams of liquid formulation displaced per revolution of         motor=0.6284×0.91=0.571844 g

The results of real testing are shown below.

-   -   0.72 RPM=0.575397 g     -   1 RPM=0.575143 g     -   5 RPM=0.5667 g     -   20 RPM=0.5775 g     -   50 RPM=0.578 g

The calculation for the real displacement was done by taking the average of real collected data for a period of 2 minutes.

Thus, the results confirm liquid formulation can be accurately displaced using the apparatus.

EXAMPLE 3—COLOUR CHANGE TIME

To test the colour change time, the apparatus was setup to run a red liquid formulation and fibre was spun at 1% addition rate. The apparatus was stopped and disassembled (as required) and cleaned. The syringe pump 12 required very little cleaning.

The pump was then loaded with white, the apparatus reassembled and fibre spun with white at 1% LDR. There was no contamination. It took only 1% hours to complete two full colour runs. In contrast, using a system as described in WO2014/207472 to perform the same task varies in time depending on the colour being used and ranges between 5 hours and 8 hours. Thus, use of apparatus of FIGS. 1 to 3 advantageously represents a minimum saving of approximately 3.5 hours per run.

EXAMPLE 4—ASSESSMENT OF COLOUR CONTAMINATION BETWEEN RUNS

An eccentric screw pump which has previously been used to deliver a liquid colour formulation as described in WO2014/207472 was purged with vehicle for 5 hours and then filled with a red colour formulation. Similarly a piston pump which also had previously been used was subjected to the minimal cleaning described herein. Then, the respective eccentric screw pump and piston pumps were used in apparatus described to make bobbins of fibre. The fibre was visually and spectrophotometrically assessed from which it was found that the fibre produced using apparatus incorporating the eccentric screw pump was contaminated with black and the brightness curve was flattened. The comparison illustrated the high quality readily achievable using the piston pump described.

EXAMPLE 5—VISCOSITY CAPABILITY

In order to use a high pressure injection apparatus in colour matching (as described hereinafter), it is important the apparatus can deliver accurately and consistently the same volume per revolution for a variety of viscosity products. To assess the pump assembly 6 of FIGS. 1 to 3, a liquid formulation comprising 80 wt % TiO₂, with a viscosity above 200,000 cP was introduced into pump 12. The formulation was then pumped at a rate of 1 rpm onto a logging balance and the data recorded.

FIG. 4 shows the actual weight of liquid formulation displaced against time. It will be noted that the pump assembly 6 perfectly displaced the highly viscous liquid formulation. When the specific gravity of the liquid formulation was considered, the pump was found to deliver 0.623 ml/rev which is exactly the theoretically predicted volume.

Pump assemblies 6 may be provided in a range of sizes for different uses and may be operated to deliver liquid formulations at different rates or pressures. One example of a pump assembly may have the following characteristic and/or may be operated as follows:

Characteristics Detail Travel per revolution (lead) 2 mm Final drive speed 0.38 rpm Radius of piston 8.5 mm Specific gravity of liquid formulation 1 g/cm³ Length of stroke of piston 300 mm Dynamic force of ball screw 3400 N Extruder throughput 8 kg/hour % addition rate of liquid formulation 0.3 wt % Ratio of gearbox associated with stepper 10 motor Motor speed 10 rpm Travel of piston per minute 0.76 mm/min Volume of liquid formulation displaced 403.56 mm³/min Area of piston 530.998 mm² Weight of liquid formulation delivered in 15 6.053 g minutes Volume of liquid formulation delivered 0.404 ml/min Pressure generated 149 bar Maximum possible volume 159.299 ml

It should now be appreciated that the apparatus described is able to deliver liquid formulations (which may incorporate relatively abrasive particles) of wide ranging viscosities, accurately and at high pressure, into molten polymeric material which may subsequently be spun on a fibre line. In view of the ease of cleaning the pump 12 in particular, the time to change colour between runs may be as short as 20 minutes, with negligible risk of colour contamination between runs. As a result of the aforesaid, the apparatus may be used in colour matching wherein quite a number of fibre samples may be produced using a range of liquid formulations and/or at different LDRs, so the samples have slightly different colours. A preferred sample may then be selected by a customer and subsequently the liquid formulation used to produce the selected sample may be delivered in production quantities to the customer. The colour matching procedure is described in more detail below.

Manufacturing polyester fibre samples in a desired colour may be divided into three separate elements—firstly, selection of a colour formulation to be used; secondly, manufacture of the colour formulation selected; and, thirdly, manufacture of fibre using the selected colour formulation. Referring to FIG. 5, the first element is represented to the left of dashed line 102; and the second element is represented to the right. Each of the elements is described in detail below.

Referring to FIG. 5, a desired colour for fibre may be determined in any of a number of first locations 104, 106, 108, 110, 112. For example, in location 104, which may be the premises of a designer or manufacturer (including a manufacturer of colourant), a customer may select a colour in which it is desired to manufacture fibre. The customer may have a sample or swatch of the desired colour. In this case, a sales-person, at location 104 with the customer, may scan the colour using a hand-held spectrophotometer. The entire visible and non-visible spectrum and any other relevant information (e.g. L*, a*, b*, DE etc.) is then sent digitally over the internet, as represented by arrow 114, to a centralised match prediction system 116. Other information which may be sent may include information on the type of polymeric material to be coloured, customer details (e.g. an identification number etc.), legislatory requirements and physical properties required (this would include fastness properties processing details etc.).

The system 116 may be located at the sales person's head office or other suitable location.

The system 116 includes a database and associated software and is able to take the spectophotometric data and predict how to reproduce the colour scanned using an associated colour dispense system. The colour dispense system includes, in one embodiment, thirty-two base colours which are arranged to be mixed in varying ratios to reproduce substantially the entire Colour Space/Spectrum. Further details on the system 116 and colour dispense system are provided hereinafter.

After receiving data relating to the spectrum of the desired colour, the system 116 determines how to match the desired colour. This step may take less than 1 minute depending on computing power. Next, information on the closest matches which can be achieved using the colour dispense system are communicated back to location 104 as represented by arrow 120. At location 104, the closest matches may then be indicated visually on a calibrated computer monitor so that the customer can see what colours can be achieved using the colour dispense system and the extent to which achievable colours differ (if they differ at all) from the desired colour. Also, system 116 may communicate additional information to location 104. For example, spectra of achievable colours may be communicated so that such spectra may be compared with the spectrum of the desired colour. Information on how achievable colours differ from the desired colour may be communicated (e.g. achievable colour is bluer, redder, lighter, darker etc. than the desired colour). Information on the cost and/or performance of formulations of achievable colours may be communicated. For example, the best match may be obtained by mixing more base colours and/or more expensive base colours and may be more expensive compared to a poorer match or a poorer performing formulation which may use cheaper base colours. The customer will be able to make a direct visual comparison between colours achievable and compare the cost of using the achievable colours in order to enable a decision to be taken on which, one or a plurality of the achievable colours should be selected and the corresponding colour formulation used to produce a fibre sample(s).

The customer may select one or a plurality of achievable colours at this stage. Alternatively, further information (e.g. make a particular previously communicated achievable colour bluer, redder or whatever) may be communicated back to system 116 for the generation of further achievable colours which may again be communicated to location 104.

In general terms, a dispense system is used to prepare liquid colour formulations for use in producing fibre samples. The colour dispense system comprises up to thirty-two separate receptacles each of which contains a respective one of thirty-two base formulations. The base formulations suitably comprise liquid (suitably organic liquid) single colourant or additive dispersions of pigments or dyes or other additives. Base formulations may include a liquid carrier base and a liquid stabiliser base. The base formulations are selected to be stable rheologically and/or colourmetrically over time (e.g. they do not significantly thicken or change or develop different colours over time) so that when incorporated into a liquid colour formulation for addition to a polymer their colour/effect is entirely predictable and will not be affected by the time or temperature of dispense etc.

Each base formulation is provided in a respective receptacle which includes associated pipework for extracting formulation from the receptacle, circulating it and returning it to the receptacle in order to maintain the formulation in a homogenous state, for example as an homogenous dispersion and to avoid any settling of any particles in the formulation.

Each of the receptacles is connected via respective pipework to a dispense station. The dispense station is computer controlled and arranged to control the accurate dispense of fluid from the receptacles into a product receptacle in order to produce a desired formulation in accordance with information determined by the centralised match prediction system 116.

Once one or a plurality of liquid formulations has been prepared, they may be delivered using the apparatus of FIGS. 1 to 3 into molten polymeric material which is then spun to produce fibre. As described, a number of fibre samples can be produced over a relatively short period of time due to the efficiency with which the apparatus of FIGS. 1 to 3 can be used. The fibre samples produced can then be passed to the customer who may select a preferred fibre. The customer may then order sufficient liquid formulation for use in a production run for producing fibre.

It should be appreciated that use of the apparatus of FIGS. 1 to 3 allows many samples to be produced on a daily basis thereby allowing customers' sample requests to be rapidly processed.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. 

1. Injection apparatus for injecting a fluid formulation into a molten polymeric material, the apparatus comprising: (a) a drive pump, said drive pump comprising a chamber for containing fluid formulation to be injected and a drive member, said drive member being linearly moveable within the chamber to drive fluid formulation downstream of the drive member to an outlet of the drive pump; (b) an injector device downstream of the outlet of the drive pump and being arranged to inject fluid formulation received from said drive pump into molten polymeric material.
 2. Apparatus according to claim 1, wherein said drive pump is arranged to deliver fluid formulation at a pressure of at least 30 bar.
 3. Apparatus according to claim 1, wherein said chamber of said drive pump has a maximum volume arranged to contain fluid formulation of less than 500 ml, a minimum volume of at least 50 ml, and/or a diameter of at least 10 mm and/or a length of at least 10 cm and less than 50 cm.
 4. (canceled)
 5. (canceled)
 6. Apparatus according to claim 1, wherein said drive member has a contact face which is arranged to contact fluid formulation in use and drive it to said outlet of said drive pump wherein said contact face is substantially planar across its entire extent.
 7. Apparatus according to claim 6, wherein, when said drive member is in a second position defining a minimum volume of said chamber, said contact face contacts an outlet face of said chamber, wherein said outlet face includes an outlet via which fluid formulation can exit the chamber wherein, when in said second position, there is no gap defined between any planar part of said contact face and any planar part of said outlet face.
 8. Apparatus according to claim 1, wherein said drive member of said drive pump is operatively connected to a force applying device which is arranged to apply a force to the drive member to cause it to move within the chamber towards said outlet, wherein said force applying device is arranged to apply a linear force of at least 1000N to the drive member.
 9. Apparatus according to claim 8, wherein said force applying device includes a drive screw which is axially aligned with an elongate axis of the drive member, wherein a motor is provided to apply a linear force to the drive member, wherein a rotational axis of said motor, an elongate axis of said drive screw and said drive member are axially aligned.
 10. (canceled)
 11. Apparatus according to claim 1, wherein said injector device includes a valve which is arranged to be opened or closed for controlling passage of fluid formulation downstream of the device, wherein said valve is arranged to withstand a fluid pressure of at least 100 bar.
 12. (canceled)
 13. Apparatus according to claim 1, wherein said drive pump is releasably securable to said injector device.
 14. Apparatus according to claim 1, wherein said injection apparatus is provided in combination with polymer supply apparatus for supplying molten polymeric material.
 15. Apparatus according to claim 10, wherein said injection apparatus is provided in combination with a mixer arranged to mix fluid formulation injected from said injection device and molten polymeric material.
 16. Apparatus according to claim 1, wherein said apparatus is provided in combination with a polymeric material forming device in which polymeric material is formed into a solid product.
 17. Apparatus according to claim 1, wherein a processing unit is associated with said injection apparatus, wherein the unit is programmed so that an operator can set the rate of delivery of fluid formulation from said injection apparatus; and/or the unit is arranged to open and/or close a valve associated with said injection device for controlling passage of fluid formulation into molten polymer material; and/or the unit is arranged to receive information relating to the pressure of liquid formulation in the injection apparatus and/or the pressure of molten polymeric material associated with polymer supply apparatus.
 18. Apparatus according to claim 1, wherein a user-interface is associated with the injection apparatus, wherein said user interface communicates with said processing unit and wherein the apparatus is arranged for input of one or more of the following variables via said user interface: the rate of throughput of polymeric material in a polymer supply apparatus; the identity and/or characteristics of the drive pump used; the specific gravity of the fluid formulation to be injected; and the desired addition rate of fluid formulation into the polymeric material.
 19. Apparatus according to claim 1, which includes a fluid formulation within said chamber and which includes a thermoplastic polymeric material in a polymer supply apparatus which is provided in combination with said injection apparatus.
 20. A method of injecting a fluid formulation into a molten polymeric material using the injection apparatus according to claim 1, the method comprising: (i) selecting an injection apparatus comprising a drive pump, said drive pump comprising a chamber containing fluid formulation to be injected and a drive member, said drive member being linearly moveable within the chamber to drive fluid formulation downstream of the drive member to an outlet of the drive pump; (ii) operating the drive pump to drive fluid formulation towards molten polymeric material; and (iii) injecting said fluid formulation into molten polymeric material.
 21. (canceled)
 22. A method according to claim 20, wherein said formulation includes 15 to 80 wt % of vehicle and 20 to 85 wt % of additives; and wherein in step (iii), fluid formulation is injected into molten polymeric material at a pressure of at least 30 bar; and wherein prior to step (iii), inputting the let-down-ratio (LDR) into a processing unit via a user interface; and inputting a desired dose rate, or information relating to a desired dose rate, at which the fluid formulation is to be dosed into the molten material; and wherein downstream of step (iii), polymeric material after contact with said fluid formulation is melt processed. 23-29. (canceled)
 30. A method of selecting a colour formulation for manufacturing, in a selected colour, a sample wherein said sample comprises a polymeric material, the method comprises: (i) selection of a first trial colour formulation; (ii) injecting said first trial colour formulation into a molten polymeric material using the injection apparatus of claim 1, said injection apparatus comprising a drive pump, said drive pump comprising a chamber for containing fluid formulation to be injected and a drive member, said drive member being linearly moveable within the chamber to drive fluid formulation downstream of the drive member to an outlet of the drive pump; (iii) after said injection, producing said sample; (iv) assessing said sample produced to determine if its colour is acceptable; (v) optionally selecting one or more other trial colour formulations or selecting a different let-down-ratio (LDR) for injection into molten polymeric material and repeating steps (ii) to (iv) until it is determined that the colour of the sample is acceptable.
 31. Apparatus according to claim 1, wherein: a drive member of said drive pump is operatively connected to a force applying device which is arranged to apply a force to the drive member to cause it to move within the chamber towards said outlet, wherein said force applying device is arranged to apply a linear force of at least 1000N to the drive member; said injector device including a valve which is arranged to be opened or closed for controlling passage of fluid formulation downstream of the device, wherein said valve is arranged to withstand a fluid pressure of at least 100 bar; said drive pump is releasably securable to said injector device; said injection apparatus is provided in combination with a melt-processing apparatus for supplying molten polymeric material; and a processing unit is associated with said injection apparatus, wherein the unit is programmed so that an operator can set the rate of delivery of fluid formulation from said injection apparatus; and/or the unit is arranged to open and/or close a valve associated with said injection device for controlling passage of fluid formulation into molten polymer material; and/or the unit is arranged to receive information relating to the pressure of liquid formulation in the injection apparatus and/or the pressure of molten polymeric material associated with polymer supply apparatus.
 32. Apparatus according to claim 1, wherein: said drive pump is arranged to deliver fluid formulation at a pressure of at least 100 bar; said chamber of said drive pump has a maximum volume arranged to contain fluid formulation of less than 500 ml; said drive member has a contact face which is arranged to contact fluid formulation in use and drive it to said outlet of said drive pump wherein said contact face is substantially planar across its entire extent; and when said drive member is in a second position defining a minimum volume of said chamber, said contact face contacts an outlet face of said chamber, wherein said outlet face includes an outlet via which fluid formulation can exit the chamber when in said second position, and wherein there is no gap defined between any planar part of said contact face and any planar part of said outlet face. 